Abstract

This study evaluates the possibility of a cascade failure by developing a coupled breach-modeling platform based on onedimensional flow modeling of the river channel, flood propagation, regulation process of reservoir fluctuation, overtopping with breaching, and wave damping downstream. A hyperbolic model of the DB-IWHR was embedded into the platform to simulate the dam breaching process. Five breach models and software were used to calculate the Tangjiashan barrier lake breaching. The results of a sensitivity study were then compared with the measured data. The peak flow and the time of occurrence were confirmed to be predictable with a reasonable accuracy if the input values were within ranges appropriate for the model. The approach was applied to a case involving two layout planning schemes for a cascade of rock-filled dams under extreme operating conditions. The probability of the failure of a key control cascade downstream caused by a continuous cascade breach upstream was simulated. Moreover, measures to prevent the transmission of risk by advance warnings were investigated. The proposed methodology and the discharge capacity measures provide guidelines to assess the risk to a cascade of dams under extreme operating conditions and offer support for the design criteria of unusual discharge structures for very large dams.